Oral microbiota: A new view of body health

Oral microbiota in cancer: could the bad guy turn good with application of polyphenols?

The human oral cavity is comprised of dynamic and polynomial microbes which uniquely reside in the microenvironments of oral cavities. The cumulative functions of the symbiotic microbial communities maintain normal homeostasis; however, a shifted microbiota yields a dysbiosis state, which produces local and systemic diseases including dental caries, periodontitis, cancer, obesity and diabetes. Recent research reports claim that an association occurs between oral dysbiosis and the progression of different types of cancers including oral, gastric and pancreatic ones. Different mechanisms are proposed for the development of cancer, such as induction of inflammatory reactions, production of carcinogenic materials and alteration of the immune system. Medications are available to treat these associated diseases; however, the current strategies may further worsen the disease by unwanted side effects. Natural-derived polyphenol molecules significantly inhibit a wide range of systemic diseases with fewer side effects. In this review, we have displayed the functions of the oral microbes and we have extended the report regarding the role of polyphenols in oral microbiota to maintain healthy conditions and prevention of diseases with emphasis on the treatment of oral microbiota-associated cancer.

USE OF MOUTHWASH AND DENTIFRICE CONTAINING AN ANTIMICROBIAL PHTHALOCYANINE DERIVATIVE FOR THE REDUCTION OF CLINICAL SYMPTOMS OF COVID-19: A RANDOMIZED TRIPLE-BLIND CLINICAL TRIAL

PURPOSE

This clinical trial aimed to evaluate the use of mouthwash and dentifrice containing an antimicrobial phthalocyanine derivative (APD) to reduce the clinical symptoms in patients with COVID-19.

METHODS

This randomized, triple-blind clinical trial enrolled 134 patients aged 18 years or older who underwent COVID-19 testing through the use of nasopharyngeal swab RT-qPCR in a reference center for the diagnosis of COVID-19, had no clinical contraindications to mouthwash and gargle, and had access to cell phones with communication applications. According to the use of a mouthwash and dentifrice containing antimicrobial phthalocyanine derivatives (APD), patients were randomly assigned (1:1) to the APD or non-APD (control) group. All participants were instructed to floss twice a day, brush teeth for 2 minutes 3 times a day, and gargle/rinse (5 mL) for 1 min/3 times a day for 7 days. An online questionnaire was sent to collect data on the clinical symptoms of COVID-19 3 times: T0 (baseline before using the oral hygiene products), T3 (3 days after), and T7 (7 days after). The investigators, patients, and outcome assessors were blinded to group assignment. The Mann-Whitney, Chi-Square, Fisher's exact, and Cochran's tests were used according to the nature of the variables studied, with the level of significance set at P < .05.

RESULTS

No statistically significant difference was found in the prevalence of symptoms between groups at baseline. A statistically significant reduction in clinical symptoms was found in the control group (fatigue, shortness of breath, hoarse voice, sore throat, nasal congestion, and chest pain) and APD group (cough, fatigue, shortness of breath, hyposmia/anosmia, dysgeusia, hoarse voice, sore throat, nasal congestion, chest pain, diarrhea, and irritability/confusion) during the follow-up period. There were statistically significant differences, with a higher prevalence of symptoms in the control group at T3 and T7. Dysgeusia, sore throat, and irritability/confusion were less prevalent in the APD group at T3, and shortness of breath, hyposmia/anosmia, dysgeusia, hoarse voice, sore throat, diarrhea, and irritability/confusion were more prevalent in the control group at T7.

CONCLUSIONS

Based on this methodology, the results demonstrated that the regular use of mouthwash and dentifrice-containing APD had a positive impact on the clinical symptoms, as reported by patients with COVID-19.

The antibiofilm activity of selected substances used in oral health prophylaxis

Oral health is a window to a patient’s general well-being. Balance in oral microbiome functions is crucial for health maintenance. A state of oral dysbiosis may lead to a variety of local and systemic pathological conditions. The presence of dental plaque is related to the majority of oral infections. Proper oral hygiene is crucial and the most economic practice contributing to oral health prophylaxis. Aside from prophylactic treatments provided by dental practitioners, mouth rinses, containing antimicrobial agents, are one of the possible tools used for oral care. Our study was to determine whether available mouth rinses and selected products dedicated for professional use are efficient to eradicate biofilm formed by reference and clinical strains of Streptococcus mutans, Streptococcus sanguinis, Streptococcus oralis, Streptococcus mitis, Staphylococcus aureus, Enterococcus faecalis, Lactobacillus rhamnosus and Candida albicans on the surface of hydroxyapatite – major mineral component of a tooth. Therefore, such antimicrobials as chlorhexidine, cetylpyridine chloride, polyhexanide, silver nanoparticles, sulphonated phenolics, and natural antiplaque essential oils and coconut oil were analyzed. Applied experimental settings in in vitro models were designed to reflect accurately the recommended use of the tested substances, therefore four types of eradication procedure were conducted. Sialorrhea simulation was also performed to evaluate antibiofilm potential of diluted mouth rinses. Biofilm was investigated with quantitative method where absorbance values were measured. Statistical differences were assessed using the Kruskal–Wallis test with a post-hoc Dunnett’s analysis. Results have shown that biofilms displayed a diversified sensitivity to the tested antimicrobials. The highest antibiofilm activity was detected for cetylpyridine chloride while the lowest for chlorhexidine. However the differences in E. faecalis biofilm reduction observed after the use of these two compounds were not statistically significant (p > 0.05), whereas all observed differences in S. aureus survival after exposure to the examined antimicrobial agents were statistically significant (p < 0.5). The PHMB, both in standard and in sialorrhea simulated conditions had the highest potential against streptococci. The coconut oil reduced C. albicans fungus biofilm by 65.48% but low eradication level was observed in case of bacterial biofilms. The dehydrating mechanism of action of sulfonated phenolics turned out to be ineffective against streptococcal biofilm which in turn was effectively eradicated by silver nanoparticles. The implementation of Antibiofilm Dressing's Activity Measurement method allowed to observe strain-related differences in terms of antimicrobial sensitivity. The obtained results may be introduced in everyday out-patient dental plaque prophylaxis as well as clinical environment.

Functional biomes beyond the bacteriome in the oral ecosystem

Selective constraint and pressures upon the host tissues often signifies a beneficial microbiome in any species. In the context of oral microbiome this displays a healthy microbial cosmos resisting the colonization and helps in rendering protection. This review highlights the endeavors of the oral microbiome beyond the bacteriome encompassing virome, mycobiome, protozoa and archaeomes in maintaining the oral homeostasis in health and disease. Scientific data based on the peer-reviewed publications on the microbial communities of the oral microbiome were selected and collated from the scientific database collection sites of web of science (WOS), pubmed central, Inspec etc., from 2010 to 2021 using the search key words like oral microbiome, oral microbiota, oral virome, oral bacteriome, oral mycobiome and oral archaeome. Data excluded were from conference proceedings, abstracts and book chapters. The oral homeostasis in both the health and disease conditions, mostly is balanced by the unrevealed virome, mycobiome, oral protozoa and archaeome. The review documents the need to comprehend the diversity that prevails among the kingdoms in order to determine the specific role played by each domain. Oral microbiome is also a novel research arena to develop drug and targeted therapies to treat various oro-dental infections.

Physicians' awareness of oral-systemic links and its association with physician-reported patient referral to dentists

INTRODUCTION

Physicians promote oral health by screening for oral pathologies, providing emergency help, and referring patients to dentists. The literature consistently reports a robust association between periodontal disease and systemic diseases. However, it is not fully known if physicians in Saudi Arabia are aware of the oral-systemic disease links. Therefore, the study aimed to evaluate physicians' awareness of the oral-systemic disease links and their association with patients' referral to dentists and patients' access to oral care.

METHODS

This cross-sectional study was conducted (June 2019-January 2020) on physicians working in private and public hospitals in the Eastern province of Saudi Arabia. The physicians (n = 333) responded to a paper-based self-administered and pilot-tested questionnaire which inquired about their awareness of oral-systemic disease links and patient referral to dentists. The reliability of items of oral-systemic disease links was evaluated by calculating Cronbach's alpha (0.84).

RESULTS

Most participants (92.8%) agreed/strongly agreed that oral health is associated with systemic health. Half of the sample (50.8%) referred patients to dentists during the last month. Almost 80.5% believed that more patients will be referred to the dentists because of their awareness of the oral-systemic disease links and 84% believed that more patients will access oral care services if patients were aware of the oral-systemic disease links. The participants who referred patients to the dentists during the last month (P = 0.038), believed that more patients will be referred (P = 0.001), and believed that more patients will access oral care (P = 0.003) demonstrated significantly higher oral-systemic disease links awareness score. The adjusted model showed patients' referral to dentist (OR = 1.96.10, P = 0.006) and believing in more patients accessing oral care (OR = 2.05, P = 0.044) were associated with significantly increased awareness of the oral-systemic disease links.

CONCLUSION

Most physicians in the study were aware of the oral-systemic disease links. Increased awareness of the oral-systemic disease links was significantly associated with the referral of patients to dentists and belief in improved patients' access to oral care services.

Nutritional factors influencing microbiota-mediated colonization resistance of the oral cavity: A literature review

The oral cavity is a key biocenosis for many distinct microbial communities that interact with both the external environment and internal body systems. The oral microbiota is a vital part of the human microbiome. It has been developed through mutual interactions among the environment, host physiological state, and microbial community composition. Indigenious microbiota of the oral cavity is one of the factors that prevent adhesion and invasion of pathogens on the mucous membrane, i.e., the development of the infectious process and thereby participating in the implementation of one of the mechanisms of local immunity-colonization resistance. The balance between bacterial symbiosis, microbial virulence, and host resistance ensures the integrity of the oral cavity. In this review we have tried to address how nutritional factors influence integrity of the oral indigenous microbiota and its involvement in colonization resistance.

Oral microbiota analyses of Saudi sickle cell anemics with dental caries

OBJECTIVES

The objectives of this study were to identify the composition of oral microbiota in a cohort of patients with sickle cell anemia (SCA) and a high mean number of decayed, missing, and filled permanent teeth (DMFT) and compare it to a cohort of patients with SCA and a low number of DMFT and elucidate the effect of fetal haemoglobin levels on the oral microbiota composition.

METHODS

Patients who had been diagnosed with SCA, who were homozygous for sickling β-globin mutation (β^S/β^S), who had Arab-Indian haplotype, and who ranged in age from 5 to 12 years were included in this study. Oral saliva from each participant (n = 100) was collected in GeneFiX™ Saliva DNA Microbiome Collection tube and DNA was extracted using GeneFiX™ DNA Isolation Kits. The composition of oral 16S rRNA from patients with SCA and high dental caries (n = 27, DMFT ≥5) and low dental caries (n = 73, DMFT ≤4) was analysed. Sequencing was performed on an Ion Personal Genome Machine using, Ion PGM Hi-Q view Sequencing 400-bp kit.

RESULTS

We observed an overall increase in abundance of Proteobacteria, Chloroflexi, and Bacteroidetes in the high DMFT index group compared to those with a low DMFT index. In addition, there was an overall increased abundance of microbiota from Proteobacteria, Fusobacteria, Firmicutes, and Bacteroidetes in the patients with SCA with low fetal haemoglobin compared to those with high fetal haemoglobin (P < .05). Enterobacteriaceae species were the most significant abundant species of bacteria found in both the high DMFT index group and low fetal haemoglobin cohort (P < .05).

CONCLUSIONS

Our data indicate that SCA in Saudi patients with high DMFT have a higher predominance of pathogenic bacteria compared to those with low DMFT. Furthermore, SCA in Saudi patients with low fetal haemoglobin have a higher predominance of pathogenic bacteria compared to those with higher fetal haemoglobin.

Your health is in your mouth: A comprehensive view to promote general wellness

Background

Even though various studies recognize the importance of the oral cavity to have general health, in multidisciplinary professional practice it is almost always excluded and on an individual basis, very commonly neglected. Oral diseases are preventable, still, they are highly prevalent. Although some studies consider oral health within integral health, currently, there is no model in which the mouth is integrated within other levels for the achievement of well-being. The objective of this article was to review the importance of oral health and its connection with well-being and, based on these findings, propose a complex and comprehensive perspective for approach and care.

Methods

The databases MEDLINE, PubMed, and Google Scholar were revised for randomized controlled trials and reviews that included search terms related to oral health and its relationship with the general health in its different levels (physical, psychological, social and environmental).

Results

The review shows that oral health is critical, as the teeth and mouth are not only an integral part of the body, but also, they also support and enable essential human functions. That is, oral health has a multidimensional nature, as it includes the physical, psychological, social, and environmental domains that are essential for overall health and well-being. Likewise, the mouth is the psychological seat of the first physiological needs and emotional gratifications, with it we take a taste of the world around us. Thus, the mouth plays an important role in the feeling of unity and in the constitution of the self. Based on these results we propose an integrative model in which the mouth is the first step for well-being and from this integrative model we build a multidisciplinary approach which could be used in the clinical practice for the promotion of oral care and general health.

Conclusion

The effort on the part of oral health professionals is essential for people's well-being and must be integrated as part of health promotion. Dental treatments alone cannot solve this problem, it requires a comprehensive and approach in which the bio-psychological, behavioral, and socio-environmental determinants are included to face this global oral health challenge. That is, without a comprehensive and multidisciplinary approach to medical science that includes dental and oral health, our public policies cannot provide the best answers to health promotion, disease prevention, early detection, and treatment.

The interplay between Helicobacter pylori and the gut microbiota: An emerging driver influencing the immune system homeostasis and gastric carcinogenesis

The human gut microbiota are critical for preserving the health status because they are required for digestion and nutrient acquisition, the development of the immune system, and energy metabolism. The gut microbial composition is greatly influenced by the colonization of the recalcitrant pathogen Helicobacter pylori (H. pylori) and the conventional antibiotic regimens that follow. H. pylori is considered to be the main microorganism in gastric carcinogenesis, and it appears to be required for the early stages of the process. However, a non-H. pylori microbiota profile is also suggested, primarily in the later stages of tumorigenesis. On the other hand, specific groups of gut microbes may produce beneficial byproducts such as short-chain fatty acids (acetate, butyrate, and propionate) that can modulate inflammation and tumorigenesis pathways. In this review, we aim to present how H. pylori influences the population of the gut microbiota to modify the host immunity and trigger the development of gastric carcinogenesis. We will also highlight the effect of the gut microbiota on immunotherapeutic approaches such as immune checkpoint blockade in cancer treatment to present a perspective for further development of innovative therapeutic paradigms to prevent the progression of H. pylori-induced stomach cancer.

Oral Microbiota, Its Equilibrium and Implications in the Pathophysiology of Human Diseases: A Systematic Review

Imbalances of the oral microbiota and dysbiosis have traditionally been linked to the occurrence of teeth and oral diseases. However, recent findings indicate that this microbiota exerts relevant influence in systemic health. Dysbiosis of the oral microbiota is implicated in the apparition and progression of cardiovascular, neurodegenerative and other major human diseases. In fact, the oral microbiota are the second most diverse and largely populated microbiota of the human body and its relationships with systemic health, although widely explored, they still lack of proper integration. The purpose of this systematic review is thus to widely examine the implications of oral microbiota in oral, cardiovascular and neurodegenerative diseases to offer integrative and up-to-date interpretations. To achieve that aim, we identified a total of 121 studies curated in PUBMED from the time interval January 2003–April 2022, which after careful screening resulted in 79 studies included. The reviewed scientific literature provides plausible vias of implication of dysbiotic oral microbiota in systemic human diseases, and encourages further research to continue elucidating the highly relevant and still poorly understood implications of this niche microbiota in systemic health. PROSPERO Registration Number: CRD42022299692. This systematic review follows relevant PRISMA guidelines.

The role of oral microbiome in periodontitis under diabetes mellitus

Periodontitis is among most common human inflammatory diseases and characterized by destruction of tooth-supporting tissues that will eventually lead to tooth loss. Diabetes mellitus (DM) is a group of metabolic disorders characterized by chronic hyperglycemia which results from defects in insulin secretion and/or insulin resistance. Numerous studies have provided evidence for the inter-relationship between DM and periodontitis that has been considered as the sixth most frequent complication of DM. However, the mechanisms are not fully understood yet. The impact of DM on periodontitis through hyperglycemia and inflammatory pathways is well described, but the effects of DM on oral microbiota remain controversial according to previous studies. Recent studies using next-generation sequencing technology indicate that DM can alter the biodiversity and composition of oral microbiome especially subgingival microbiome. This may be another mechanism by which DM risks or aggravates periodontitis. Thus, to understand the role of oral microbiome in periodontitis of diabetics and the mechanism of shifts of oral microbiome under DM would be valuable for making specific therapeutic regimens for treating periodontitis patients with DM or preventing diabetic patients from periodontitis. This article reviews the role of oral microbiome in periodontal health (symbiosis) and disease (dysbiosis), highlights the oral microbial shifts under DM and summarizes the mechanism of the shifts.

Oral Microbes in Hospital-Acquired Pneumonia: Practice and Research Implications

BACKGROUND

Hospital-acquired pneumonia accounts for 25% of all health care-associated infections and is classified as either ventilator-associated or non-ventilator-associated pneumonia. Hospital-acquired pneumonia most frequently results from aspiration of oropharyngeal secretions into the lungs. Although preventive measures for ventilator-associated pneumonia are well established, few preventive measures exist for the nonventilator type.

OBJECTIVE

To (1) explore oral microbes associated with ventilator-associated and non-ventilator-associated pneumonia in acutely ill, adult hospitalized patients, and (2) provide evidence-based recommendations for measures to prevent pneumonia in hospitalized patients.

METHODS

A literature search was conducted using CINAHL, Academic Search Premier, Medline, and the Cochrane Library.

RESULTS

Ten studies were found that identified common oral microbes in ventilator-associated and non-ventilator-associated pneumonia, including Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, S aureus, and Streptococcus pneumoniae. Collectively, oral colonization with E coli, P aeruginosa, methicillin-resistant S aureus, and S aureus increased the risk of nonventilator pneumonia. Findings also suggested microaspiration of colonized oral microbes into the lungs. Non-ventilator-associated pneumonia had similar colonization rates of gram-positive and gram-negative bacteria, whereas ventilator-associated pneumonia had greater colonization with gram-negative bacteria. The literature did not indicate a standard of oral care effective in all patient populations.

DISCUSSION

Oral care is an effective intervention to prevent hospital-acquired pneumonia by reducing pathogenic oral microbial colonization. The impact of different methods and timing of oral care on oral microbes should be further explored, particularly in patients not receiving mechanical ventilation.

CONCLUSIONS

Findings reaffirm the importance of consistent oral care in hospitalized patients. In addition, practices should be different in patients receiving mechanical ventilation versus patients not receiving ventilation. Results may also provide knowledge to inform future preventive measures for pneumonia, particularly for nonventilator pneumonia.

The Impact of Alcohol-Induced Dysbiosis on Diseases and Disorders of the Central Nervous System

The human digestive tract contains a diverse and abundant microbiota that is important for health. Excessive alcohol use can disrupt the balance of these microbes (known as dysbiosis), leading to elevated blood endotoxin levels and systemic inflammation. Using QIAGEN Ingenuity Pathway Analysis (IPA) bioinformatics tool, we have confirmed that peripheral endotoxin (lipopolysaccharide) mediates various cytokines to enhance the neuroinflammation signaling pathway. The literature has identified alcohol-mediated neuroinflammation as a possible risk factor for the onset and progression of neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson's disease (PD), and psychiatric disorders such as addiction to alcohol and other drugs. In this review, we discuss alcohol-use-induced dysbiosis in the gut and other body parts as a causal factor in the progression of Central Nervous System (CNS) diseases including neurodegenerative disease and possibly alcohol use disorder.

The oral microbiome, nitric oxide and exercise performance

The human microbiome comprises ∼10¹³-10¹⁴ microbial cells which form a symbiotic relationship with the host and play a critical role in the regulation of human metabolism. In the oral cavity, several species of bacteria are capable of reducing nitrate to nitrite; a key precursor of the signaling molecule nitric oxide. Nitric oxide has myriad physiological functions, which include the maintenance of cardiovascular homeostasis and the regulation of acute and chronic responses to exercise. This article provides a brief narrative review of the research that has explored how diversity and plasticity of the oral microbiome influences nitric oxide bioavailability and related physiological outcomes. There is unequivocal evidence that dysbiosis (e.g. through disease) or disruption (e.g. by use of antiseptic mouthwash or antibiotics) of the oral microbiota will suppress nitric oxide production via the nitrate-nitrite-nitric oxide pathway and negatively impact blood pressure. Conversely, there is preliminary evidence to suggest that proliferation of nitrate-reducing bacteria via the diet or targeted probiotics can augment nitric oxide production and improve markers of oral health. Despite this, it is yet to be established whether purposefully altering the oral microbiome can have a meaningful impact on exercise performance. Future research should determine whether alterations to the composition and metabolic activity of bacteria in the mouth influence the acute responses to exercise and the physiological adaptations to exercise training.

Ceragenin CSA-44 as a Means to Control the Formation of the Biofilm on the Surface of Tooth and Composite Fillings

Recurrent oral infections, as manifested by endodontic and periodontal disease, are often caused by Enterococcus faecalis (E. faecalis) and Candida albicans (C. albicans). Here, we assessed the anti-biofilm activity of ceragenin CSA-44 against these microbes growing as a biofilm in the presence of saliva on the surface of human teeth and dental composite (composite filling) subjected to mechanical stresses. Methods: Biofilm mass analysis was performed using crystal violet (CV) staining. The morphology, viscoelastic properties of the biofilm after CSA-44 treatment, and changes in the surface of the composite in response to biofilm presence were determined by AFM microscopy. Results: CSA-44 prevented biofilm formation and reduced the mass of biofilm formed by tested microorganisms on teeth and dental composite. Conclusion: The ability of CSA-44 to prevent the formation and to reduce the presence of established biofilm on tooth and composite filling suggests that it can serve as an agent in the development of new methods of combating oral pathogens and reduce the severity of oral infections.

Regulation of oxytocin receptor gene expression in obsessive-compulsive disorder: a possible role for the microbiota-host epigenetic axis

BACKGROUND

Obsessive-compulsive disorder (OCD) is a prevalent and severe clinical condition. Robust evidence suggests a gene-environment interplay in its etiopathogenesis, yet the underlying molecular clues remain only partially understood. In order to further deepen our understanding of OCD, it is essential to ascertain how genes interact with environmental risk factors, a cross-talk that is thought to be mediated by epigenetic mechanisms. The human microbiota may be a key player, because bacterial metabolites can act as epigenetic modulators. We analyzed, in the blood and saliva of OCD subjects and healthy controls, the transcriptional regulation of the oxytocin receptor gene and, in saliva, also the different levels of major phyla. We also investigated the same molecular mechanisms in specific brain regions of socially isolated rats showing stereotyped behaviors reminiscent of OCD as well as short chain fatty acid levels in the feces of rats.

RESULTS

Higher levels of oxytocin receptor gene DNA methylation, inversely correlated with gene expression, were observed in the blood as well as saliva of OCD subjects when compared to controls. Moreover, Actinobacteria also resulted higher in OCD and directly correlated with oxytocin receptor gene epigenetic alterations. The same pattern of changes was present in the prefrontal cortex of socially-isolated rats, where also altered levels of fecal butyrate were observed at the beginning of the isolation procedure.

CONCLUSIONS

This is the first demonstration of an interplay between microbiota modulation and epigenetic regulation of gene expression in OCD, opening new avenues for the understanding of disease trajectories and for the development of new therapeutic strategies.

Oral-Gut Microbiome Axis in the Pathogenesis of Cancer Treatment-Induced Oral Mucositis

Oral mucositis (OM) is one of the most common and debilitating oral complications of cancer treatments including chemotherapy, radiotherapy, and hematopoietic stem cell transplantation. It is associated with severe pain and difficulties in chewing, swallowing, and speech. This leads to impairment of basic oral functions and could result in unplanned treatment interruption or modification. As such, OM negatively impacts both patients' quality of life as well as tumor prognostic outcomes. Understanding pathways underlying OM pathogenesis help identify new targets for intervention or prevention. The pathophysiology of OM has been widely studied over past decades with several pathways related to oxidative stress, inflammation, and molecular and cellular signaling being implicated. In this mini-review, we will discuss the emerging role of the oral-gut microbiome axis in the development of OM. Particularly, we will elaborate on how the alterations in the oral and gut microbiota as well as intestinal dysfunction caused by cancer treatments could contribute to the pathogenesis of OM. Further, we will briefly discuss the potential methods for targeting the oral-gut microbiome axis to improve OM outcomes.

Environmental and Human Microbiome for Health

Microorganisms are an essential part of life on the earth and can exist in association with virtually any living thing. The environmental microbiome is much more diverse than the human microbiome. It is reported that most microbes existing in the environment are difficult to culture in the laboratory. Whereas both pathogenic and beneficial microbes may be prevailing in the environment, the human body can have three categories of microbes- beneficial, pathogenic, and opportunistic pathogenic. With at least 10-fold more cells than human cells, microbes as normal flora are critical for human survival. The microbes present in the human body play a crucial role in maintaining human health, and the environmental microbiome influences the human microbiome makeup. The interaction between the environmental and human microbiome highly influences human health, however it is poorly understood. In addition, as an established infection is associated with health-seeking behavior, a large number of studies have focused on the transmission and dynamics of infectious microorganisms than the noninfectious or beneficial ones. This review will summarize how the interaction between the environmental and human microbiome affects human health and identify approaches that might be beneficial for humans to improve health by being exposed to the natural environment.

A Potential “Vitaminic Strategy” against Caries and Halitosis

Streptococcus mutans and Fusobacterium nucleatum are two key bacteria of the oral microbiota. Due to their ability to form biofilms on oral tissues, they are both involved in the onset of the most common oral diseases. F. nucleatum is also the principal producer of hydrogen sulfide (H2S), causative of the awkward bad breath of halitosis. In this study, the oral product Vea® Oris, made by vitamin E and capric/caprylic acid only, was evaluated as a potential treatment for the most common oral diseases. Different concentrations of the product were tested against both S. mutans and F. nucleatum. The effect on planktonic and biofilm growth was investigated for both strains, and for F. nucleatum, the influence on H2S production was evaluated. From our data, the product did not relevantly reduce the planktonic growth of both strains, whereas it validly counteracted biofilm assemblage. Moreover, an interesting trend of H2S reduction was highlighted. Overall, these results suggested, on the one hand, a synergistic antimicrobial–antibiofilm action of two Vea® Oris components and, together, potential modulation activity on H2S production. However, the study should be implemented to confirm these only preliminary findings, certainly extending the panel of tested bacteria and using alternative methods of detection.

Dietary Correlates of Oral and Gut Microbiota in the Water Monitor Lizard, Varanus salvator (Laurenti, 1768)

Numerous studies have demonstrated that food shapes the structure and composition of the host’s oral and gut microbiota. The disorder of oral and gut microbiota may trigger various host diseases. Here, we collected oral and gut samples from wild water monitor lizards (Varanus salvator) and their captive conspecifics fed with bullfrogs, eggs, and depilated chicken, aiming to examine dietary correlates of oral and gut microbiota. We used the 16S rRNA gene sequencing technology to analyze the composition of the microbiota. Proteobacteria and Bacteroidota were the dominant phyla in the oral microbiota, and so were in the gut microbiota. The alpha diversity of microbiota was significantly higher in the gut than in the oral cavity, and the alpha diversity of oral microbiota was higher in captive lizards than in wild conspecifics. Comparing the relative abundance of oral and gut bacteria and their gene functions, differences among different animal groups presumably resulted from human contact in artificial breeding environments and complex food processing. Differences in gene function might be related to the absolute number and/or the taxonomic abundance of oral and gut microorganisms in the wild and the water environment. This study provides not only basic information about the oral and gut microbiota of captive and wild water monitor lizards, but also an inference that feeding on frogs and aquatic products and reducing human exposure help water monitor lizards maintain a microbiota similar to that in the wild environment.

A. muciniphila Supplementation in Mice during Pregnancy and Lactation Affects the Maternal Intestinal Microenvironment

During pregnancy and lactation, considerable factors that affect the maternal microbiome are associated with the advancement of numerous diseases, which can potentially affect offspring health. Probiotics have shown potential for the maintenance of microbiota homeostasis of mothers in this period. The specific objective of this study was to investigate whether the application of Akkermansia muciniphila (A. muciniphila) during pregnancy and lactation impacts maternal and offspring health. Here we show that dams fed with A. muciniphila is safe, enhances the intestinal barrier and alters gut microbiota composition and diversity at the end of lactation, including the significant enrichment of A. muciniphila and Ruminococcus_1 in offspring from probiotic-fed dams. However, compared with the control group, the fecal metabolites of the A. muciniphila group only changed slightly. Additionally, A. muciniphila supplementation did not significantly increase the abundance of A. muciniphila in the fecal microbiota of offspring mice. Compared with the control group, the fecal metabolic profile of three-week-old offspring of mice fed with A. muciniphila were significantly changed, containing the D-glutamine and D-glutamate metabolism pathways. These results provided evidence that A. muciniphila supplementation in mice during pregnancy and lactation is safe and seemed to have a more beneficial effect on dams. In the future, using probiotics to regulate maternal microbiomes during pregnancy and lactation could be shown to have a more lasting and beneficial effect.

Armed to the Teeth-The Oral Mucosa Immunity System and Microbiota

The oral cavity is inhabited by a wide spectrum of microbial species, and their colonization is mostly based on commensalism. These microbes are part of the normal oral flora, but there are also opportunistic species that can cause oral and systemic diseases. Although there is a strong exposure to various microorganisms, the oral mucosa reduces the colonization of microorganisms with high rotation and secretion of various types of cytokines and antimicrobial proteins such as defensins. In some circumstances, the imbalance between normal oral flora and pathogenic flora may lead to a change in the ratio of commensalism to parasitism. Healthy oral mucosa has many important functions. Thanks to its integrity, it is impermeable to most microorganisms and constitutes a mechanical barrier against their penetration into tissues. Our study aims to present the role and composition of the oral cavity microbiota as well as defense mechanisms within the oral mucosa which allow for maintaining a balance between such numerous species of microorganisms. We highlight the specific aspects of the oral mucosa protecting barrier and discuss up-to-date information on the immune cell system that ensures microbiota balance. This study presents the latest data on specific tissue stimuli in the regulation of the immune system with particular emphasis on the resistance of the gingival barrier. Despite advances in understanding the mechanisms regulating the balance on the microorganism/host axis, more research is still needed on how the combination of these diverse signals is involved in the regulation of immunity at the oral mucosa barrier.

The Role of the Western Diet and Oral Microbiota in Parkinson's Disease

The type of diet not only affects the composition of the oral microflora but is also one of the more critical factors associated with an increased risk of Parkinson’s disease, PD. This study compared diet preferences and oral microbiota profiles in patients with PD vs. healthy controls. This study compared the oral microbiota composition of 59 patients with PD and 108 healthy controls (without neurodegeneration) using 16S rRNA gene amplicon sequencing. According to results, oral microbiota in patients with PD is different compared from healthy controls. In particular, decreased abundance of Proteobacteria, Pastescibacteria, and Tenercutes was observed. The oral cavity of patients with PD was characterized by the high relative abundance of bacteria from the genera Prevotella, Streptococcus, and Lactobaccillus. There were also differences in food preferences between patients with PD and healthy controls, which revealed significantly higher intake of margarine, fish, red meat, cereals products, avocado, and olives in the patients with PD relative to healthy controls. Strong positive and negative correlations between specific food products and microbial taxa were identified.

Dental mesenchymal stromal/stem cells in different microenvironments— implications in regenerative therapy

Current research data reveal microenvironment as a significant modifier of physical functions, pathologic changes, as well as the therapeutic effects of stem cells. When comparing regeneration potential of various stem cell types used for cytotherapy and tissue engineering, mesenchymal stem cells (MSCs) are currently the most attractive cell source for bone and tooth regeneration due to their differentiation and immunomodulatory potential and lack of ethical issues associated with their use. The microenvironment of donors and recipients selected in cytotherapy plays a crucial role in regenerative potential of transplanted MSCs, indicating interactions of cells with their microenvironment indispensable in MSC-mediated bone and dental regeneration. Since a variety of MSC populations have been procured from different parts of the tooth and tooth-supporting tissues, MSCs of dental origin and their achievements in capacity to reconstitute various dental tissues have gained attention of many research groups over the years. This review discusses recent advances in comparative analyses of dental MSC regeneration potential with regards to their tissue origin and specific microenvironmental conditions, giving additional insight into the current clinical application of these cells.

Effect of human secretory calcium-binding phosphoprotein proline-glutamine rich 1 protein on Porphyromonas gingivalis and identification of its active portions

The mouth environment comprises the second most significant microbiome in the body, and its equilibrium is critical in oral health. Secretory calcium-binding phosphoprotein proline-glutamine rich 1 (SCPPPQ1), a protein normally produced by the gingival epithelium to mediate its attachment to teeth, was suggested to be bactericidal. Our aim was to further explore the antibacterial potential of human SCPPPQ1 by characterizing its mode of action and identifying its active portions. In silico analysis showed that it has molecular parallels with antimicrobial peptides. Incubation of Porphyromonasgingivalis, a major periodontopathogen, with the full-length protein resulted in decrease in bacterial number, formation of aggregates and membrane disruptions. Analysis of SCPPPQ1-derived peptides indicated that these effects are sustained by specific regions of the molecule. Altogether, these data suggest that human SCPPPQ1 exhibits antibacterial capacity and provide new insight into its mechanism of action.

Effects of Bacteroides-Based Microecologics against Antibiotic-Associated Diarrhea in Mice

Antibiotic-associated diarrhea (AAD) is a self-limiting disease mediated by antibiotic therapy. In clinical practice, several types of probiotics are used in treating AAD, but minimal research has been done on Bacteroides-based microecologics. Our aim was to evaluate the therapeutic effects of Bacteroidetes uniformis FGDLZ48B1, B. intestinalis FJSWX61K18, Bifidobacterium adolescentis FHNFQ48M5, and B. bifidum FGZ30MM3 and their mixture on AAD in mice. The lincomycin hydrochloride-induced AAD models were gavaged with a single strain or a probiotic mixture for a short period to assess the changes in colonic histopathology and cytokine concentrations, intestinal epithelial permeability and integrity, short-chain fatty acids (SCFAs), and the diversity of intestinal microbiota. Our data indicated that both the sole use of Bacteroides and the combination of Bacteroides and Bifidobacterium beneficially weakened systemic inflammation, increased the recovery rate of tissue structures, increased the concentrations of SCFAs, and restored the gut microbiota. Moreover, the probiotic mixture was more effective than the single strain. Specifically, B. uniformis FGDLZ48B1 combined with the B. adolescentis FHNFQ48M5 group was more effective in alleviating the pathological features of the colon, downregulating the concentrations of interleukin (IL)-6, and upregulating the expression of occludin. In summary, our research suggests that administration of a mixture of B. uniformis FGDLZ48B1 and B. adolescentis FHNFQ48M5 is an effective approach for treating AAD.

Salivary Microbiota Is Significantly Less Diverse in Patients with Chronic Spontaneous Urticaria Compared to Healthy Controls: Preliminary Results

Background: Because of the important role in regulating the immune system, increasing evidence suggests a possible implication of gut microbiota in Chronic spontaneous urticaria (CSU). Although the oral cavity is the first site of contact between microbiota and the immune system, the association between salivary microbiota and CSU has not yet been reported. Objective: This case-control study aimed to compare differences in salivary microbiota between CSU patients and healthy controls (HC). Twenty-three participants—13 patients with CSU and 10 HC were enrolled; salivary microbiota was determined by molecular approach targeting 16S ribosomal RNA. Terminal restriction fragment length polymorphism (T-RFLP) analysis was performed. Results: Alpha diversity of salivary microbiota in CSU patients was significantly reduced compared to HC, resulting in alteration of the community composition. Species richness determined via the Shannon index was significantly reduced in the CSU group. Conclusion: Dysbiosis of salivary microbiota may contribute to a dysregulated immune system in the development of CSU. To our knowledge, this was the first study that reported an alteration in salivary microbiota composition in CSU patients.

Cyclodextrin as Functional Carrier in Development of Mucoadhesive Tablets Containing Polygoni cuspidati Extract with Potential for Dental Applications

Polygoni cuspidati root is a resveratrol-rich source with anti-inflammatory, angiogenic and neuroprotective effects. The raw material was standardized for the content of resveratrol, for which there is a special justification for administration within the oral mucosa. To improve the solubility of resveratrol and to assure its high content in plant material, an ultrasound-assisted extraction method was applied. The addition of cyclodextrin was found to increase the extraction efficiency of resveratrol (from 13 to 297 µg per 1 g of plant material in case of 50% ethanol extracts) and enhanced its antioxidant activity as compared to pure Polygoni cuspidati extract/resveratrol. Cyclodextrin plays the role of a functional extract regarding technological properties (increasing the extraction of resveratrol from the extract, improving mucoadhesive properties). Therefore, the aim of this study was to develop mucoadhesive tablets containing combinations of the Polygoni cuspidati extract with a cyclodextrin carrier for buccal delivery. The tests sequentially included extract preparation and characterization of its physical and biological properties and then formulation studies with a broad description of the prototype properties. The test results indicate that cyclodextrin increases the efficiency of resveratrol extraction from Polygoni cuspidati rhizome, which is a rich source of resveratrol, and its extract enclosed in a mucoadhesive tablet guarantees prolonged action at the site of administration.

Oral, Nasal, and Gut Microbiota in Parkinson's Disease

Parkinson's disease (PD) is the second most frequently diagnosed neurodegenerative disease. The purpose of this study was to investigate the link between microbiota composition in important mucosal interfaces (oral, nasal, and intestinal) and PD. Sequencing was undertaken of the V4-V5 region of the 16S ribosomal RNA (rRNA) gene of the microbiome from the oral cavity, nasal cavity, and gut of 91 PD patients and 91 healthy controls. Significant differences were found in microbiota composition in the oral cavity and gut, but not the nasal cavity, between PD patients and healthy controls after adjusting for age, gender, and body mass index (BMI). More genera in the oral cavity were significantly positively correlated with clinical characteristics, such as the HAMA and HAMD rating scales. The taxa c_Clostridia, o_Clostridiales, and f_Ruminococcaceae in the gut microbiota were associated with weight and MMSE score. Furthermore, as a result of dysbiosis, there was an enrichment of ion channel-, oxidative phosphorylation-, and carbohydrate metabolism-related pathways in the oral cavity and glycolysis/gluconeogenesis- and propanoate metabolism-related pathways in the intestine. Changes in these pathways can influence metabolism and inflammation, thereby contributing to PD pathogenesis. In addition, several subnetworks containing differentially abundant microbiota in the oral cavity and gut samples from PD patients may regulate microbial composition and function in PD. Overall, our results indicate that oral and gut dysbiosis may affect PD progression and provide a basis for understanding the pathogenesis of PD and identifying potential therapeutic targets for the treatment of this disease.

Toll Like Receptors as Sensors of the Tumor Microbial Dysbiosis: Implications in Cancer Progression

The microbiota is a complex ecosystem of active microorganisms resident in the body of mammals. Although the majority of these microorganisms resides in the distal gastrointestinal tract, high-throughput DNA sequencing technology has made possible to understand that several other tissues of the human body host their own microbiota, even those once considered sterile, such as lung tissue. These bacterial communities have important functions in maintaining a healthy body state, preserving symbiosis with the host immune system, which generates protective responses against pathogens and regulatory pathways that sustain the tolerance to commensal microbes. Toll-like receptors (TLRs) are critical in sensing the microbiota, maintaining the tolerance or triggering an immune response through the direct recognition of ligands derived from commensal microbiota or pathogenic microbes. Lately, it has been highlighted that the resident microbiota influences the initiation and development of cancer and its response to therapies and that specific changes in the number and distribution of taxa correlate with the existence of cancers in various tissues. However, the knowledge of functional activity and the meaning of microbiome changes remain limited. This review summarizes the current findings on the function of TLRs as sensors of the microbiota and highlighted their modulation as a reflection of tumor-associated changes in commensal microbiota. The data available to date suggest that commensal "onco-microbes" might be able to break the tolerance of TLRs and become complicit in cancer by sustaining its growth.

Dogs' Microbiome From Tip to Toe

Microbiota and microbiome, which refers, respectively, to the microorganisms and conjoint of microorganisms and genes are known to live in symbiosis with hosts, being implicated in health and disease. The advancements and cost reduction associated with high-throughput sequencing techniques have allowed expanding the knowledge of microbial communities in several species, including dogs. Throughout their body, dogs harbor distinct microbial communities according to the location (e.g., skin, ear canal, conjunctiva, respiratory tract, genitourinary tract, gut), which have been a target of study mostly in the last couple of years. Although there might be a core microbiota for different body sites, shared by dogs, it is likely influenced by intrinsic factors such as age, breed, and sex, but also by extrinsic factors such as the environment (e.g., lifestyle, urban vs rural), and diet. It starts to become clear that some medical conditions are mediated by alterations in microbiota namely dysbiosis. Moreover, understanding microbial colonization and function can be used to prevent medical conditions, for instance, modulation of gut microbiota of puppies is more effective to ensure a healthy gut than interventions in adults. This paper gathers current knowledge of dogs' microbial communities, exploring their function, implications in the development of diseases, and potential interactions among communities while providing hints for further research.

Antimicrobial resistance of bacterial strains in patients undergoing orthodontic treatment with and without fixed appliances

OBJECTIVES

To identify microorganisms isolated from patients wearing fixed orthodontic appliances and to evaluate the resistance of isolated bacterial strains to different antimicrobials.

MATERIALS AND METHODS

Seventeen healthy patients wearing a fixed orthodontic appliance (group 1) and six nonwearers (group 2, control group) were evaluated. The biofilm that formed around the orthodontic brackets was collected, and the samples were then plated in a chromogenic medium (chromIDT, bioMérieux). Colony-forming units (CFUs) were isolated and inoculated in blood-agar medium. Automated biochemical tests (VITEK 2, bioMérieux) were carried out to identify the genus and species of the microorganisms and the resistance provided by 43 drugs (37 antibacterial and 6 antifungal).

RESULTS

The most prevalent microbial genera identified in group 1 were Streptococcus (24.0%), Staphylococcus (20.0%), Enterobacter (12.0%), Geobacillus (12.0%), and Candida (12.0%), and the most frequent species were Enterobacter cloacae complex (13.6%) and Staphylococcus hominis (13.6%). In group 2, the most prevalent genera were Streptococcus (57.1%), Staphylococcus (14.2%), Sphingomonas (14.2%), and Enterobacter (14.2%). With regard to antimicrobial resistance, 14 of 19 (74%) isolated bacterial strains were found to be resistant to at least 1 of the tested antimicrobials.

CONCLUSIONS

The findings of the present study suggest that patients undergoing orthodontic treatment with fixed appliances have a more complex biofilm with a higher level of bacterial resistance.

An Integrative Review of the Role of the Oral and Gut Microbiome in Oral Health Symptomatology During Cancer Therapy

PROBLEM IDENTIFICATION

Both chemotherapy and radiation therapy cause considerable symptom burden on patients' oral health, influencing nutritional status and quality of life. The role of the oral and gut microbiome in oral health alterations during cancer therapy is an emerging area of science in symptom management.

LITERATURE SEARCH

PubMed®, CINAHL®, and Scopus® were searched for articles published from January 2000 through July 2020.

DATA EVALUATION

Articles published in English that were focused on chemotherapy and/or radiation therapy were included in the review.

SYNTHESIS

Of the 22 identified studies, 12 described oral health symptoms during chemotherapy and radiation therapy for head and neck cancer. Ten studies assessed symptoms during treatment for a variety of solid tumors and blood cancers, with four of these describing microbial interventions for the management of oral mucositis. Interventions varied, but the results supported the benefits of probiotics and synbiotics in reducing mucositis severity. Overall, less diverse oral and gut microbiome environments were associated with increased severity of oral health symptomatology.

IMPLICATIONS FOR PRACTICE

Additional research is needed to determine how the oral and gut microbiome and microbial interventions may be used to improve oral health management during cancer treatment.

Synthesis and Characterization of Novel Quaternary Ammonium Urethane-Dimethacrylate Monomers-A Pilot Study

Six novel urethane-dimethacrylate analogues (QAUDMAs) were synthesized and characterized. They consisted of the 2,4,4,-trimethylhexamethylene diisocyanate (TMDI) core and two methacrylate-terminated wings containing quaternary ammonium groups substituted with alkyl chains of 8, 10, 12, 14, 16, or 18 carbon atoms. QAUDMAs, due to the presence of quaternary ammonium groups, may have possible antibacterial effects. Since they showed satisfactory physicochemical properties, they will be subjected to further research towards the development of dental composites with a capacity to reduce secondary caries. The synthesis of QAUDMAs included three stages: (i) transesterification of methyl methacrylate (MMA) with N-methyldiethanolamine (MDEA), (ii) N-alkylation of the tertiary amino group with alkyl bromide, and (iii) addition of TMDI to the intermediate achieved in the second stage. The formation of QAUDMAs was confirmed by ¹H and ¹³C NMR. They were characterized for density (d_m), viscosity (η), refractive index (RI), glass transition temperature (T_g), polymerization shrinkage (S), and degree of conversion (DC). QAUDMAs were yellow, viscous resins (the η values ranged from 1.28 × 10³ to 1.39 × 10⁴ Pa·s, at 50 °C). Their RI ranged from 1.50 to 1.52, T_g from −31 to −15 °C, DC from 53 to 78%, and S from 1.24 to 2.99%, which is appropriate for dental applications.

An Overview of Physical, Microbiological and Immune Barriers of Oral Mucosa

The oral mucosa, which is the lining tissue of the oral cavity, is a gateway to the body and it offers first-line protection against potential pathogens, exogenous chemicals, airborne allergens, etc. by means of its physical and microbiological-immune barrier functions. For this reason, oral mucosa is considered as a mirror to the health of the individual as well as a guard or early warning system. It is organized in two main components: a physical barrier, which consists of stratified epithelial cells and cell-cell junctions, and a microbiological-immune barrier that keeps the internal environment in a condition of homeostasis. Different factors, including microorganism, saliva, proteins and immune components, have been considered to play a critical role in disruption of oral epithelial barrier. Altered mucosal structure and barrier functions results in oral pathologies as well as systemic diseases. About 700 kinds of microorganisms exist in the human mouth, constituting the oral microbiota, which plays a significant role on the induction, training and function of the host immune system. The immune system maintains the symbiotic relationship of the host with this microbiota. Crosstalk between the oral microbiota and immune system includes various interactions in homeostasis and disease. In this review, after reviewing briefly the physical barriers of oral mucosa, the fundamentals of oral microbiome and oral mucosal immunity in regard to their barrier properties will be addressed. Furthermore, their importance in development of new diagnostic, prophylactic and therapeutic strategies for certain diseases as well as in the application for personalized medicine will be discussed.

Metabolites of the Oral Microbiome: Important Mediators of Multi-Kingdom Interactions

The oral cavity hosts over 700 different microbial species that produce a rich reservoir of bioactive metabolites critical to oral health maintenance. Over the last two decades, new insights into the oral microbiome and its importance in health and disease have emerged mainly due to the discovery of new oral microbial species using next-generation sequencing (NGS). This advancement has revolutionized the documentation of unique microbial profiles associated with different niches and health/disease states within the oral cavity and the relation of the oral bacteria to systemic diseases. However, less work has been done to identify and characterize the unique oral microbial metabolites that play critical roles in maintaining equilibrium between the various oral microbial species and their human hosts. This article discusses the most significant microbial metabolites produced by these diverse communities of oral bacteria that can either foster health or contribute to disease. Finally, we shed light on how advances in genomics and genome mining can provide a high throughput platform for discovering novel bioactive metabolites derived from the human oral microbiome to tackle emerging human infections and systemic diseases.

Tapioca Starch Modulates Cellular Events in Oral Probiotic Streptococcus salivarius Strains

Considering the implications of microbiota in health, scientists are in search of microbiota-oriented strategies for the effective prevention and/or treatment of a wide variety of serious diseases. A microbiota comprises diverse microorganisms with either probiotic or pathogenic properties. The fermentation of prebiotic carbohydrates by probiotic bacteria can affect host metabolism. Therefore, understanding the prebiotic-mediated metabolic modulations in probiotics is crucial to develop functional foods for the improvement of disturbed microbiota. Studies have emphasized the importance of prebiotics in probiotic therapies for mucosal diseases and highlighted the need for extensive research on oral bacteria. In the present study, the cellular events have been studied in batch cultures of probiotic Streptococcus salivarius exposed to the natural prebiotic, tapioca starch (TS). TS modulated the keystone metabolic events in Streptococcus salivarius in a dose-dependent manner. Besides increasing the live cell counts and altering the colony morphologies, TS affected the protein metabolism in terms of cellular expression and conformational changes in protein secondary structures. After treatment with TS, the nucleic acid synthesis increased and B-DNA was more than A- and Z-DNA, together with the diminished fatty acids and increased polysaccharide synthesis. The study results can be considered for the assessment of functional foods and probiotics in oral health.

Infective Endocarditis: A Focus on Oral Microbiota

Infective endocarditis (IE) is an inflammatory disease usually caused by bacteria entering the bloodstream and settling in the heart lining valves or blood vessels. Despite modern antimicrobial and surgical treatments, IE continues to cause substantial morbidity and mortality. Thus, primary prevention and enhanced diagnosis remain the most important strategies to fight this disease. In this regard, it is worth noting that for over 50 years, oral microbiota has been considered one of the significant risk factors for IE. Indeed, among the disparate recommendations from the American heart association and the European Society of Cardiology, there are good oral hygiene and prophylaxis for high-risk patients undergoing dental procedures. Thus, significant interest has grown in the role of oral microbiota and it continues to be a subject of research interest, especially if we consider that antimicrobial treatments can generate drug-resistant mutant bacteria, becoming a severe social problem. This review will describe the current knowledge about the relationship between oral microbiota, dental procedures, and IE. Further, it will discuss current methods used to prevent IE cases that originate from oral pathogens and how these should be focused on improving oral hygiene, which remains the significant persuasible way to prevent bacteremia and systemic disorders.

Investigation of Spaceflight Induced Changes to Astronaut Microbiomes

The International Space Station (ISS) is a uniquely enclosed environment that has been continuously occupied for the last two decades. Throughout its operation, protecting the health of the astronauts on-board has been a high priority. The human microbiome plays a significant role in maintaining human health, and disruptions in the microbiome have been linked to various diseases. To evaluate the effects of spaceflight on the human microbiome, body swabs and saliva samples were collected from four ISS astronauts on consecutive expeditions. Astronaut samples were analyzed using shotgun metagenomic sequencing and microarrays to characterize the microbial biodiversity before, during, and after the astronauts’ time onboard the ISS. Samples were evaluated at an individual and population level to identify changes in microbial diversity and abundance. No significant changes in the number or relative abundance of taxa were observed between collection time points when samples from all four astronauts were analyzed together. When the astronauts’ saliva samples were analyzed individually, the saliva samples of some astronauts showed significant changes in the relative abundance of taxa during and after spaceflight. The relative abundance of Prevotella in saliva samples increased during two astronauts’ time onboard the ISS while the relative abundance of other commensal taxa such as Neisseria, Rothia, and Haemophilus decreased. The abundance of some antimicrobial resistance genes within the saliva samples also showed significant changes. Most notably, elfamycin resistance gene significantly increased in all four astronauts post-flight and a CfxA6 beta-lactam marker significantly increased during spaceflight but returned to normal levels post-flight. The combination of both shotgun metagenomic sequencing and microarrays showed the benefit of both technologies in monitoring microbes on board the ISS. There were some changes in each astronaut’s microbiome during spaceflight, but these changes were not universal for all four astronauts. Two antimicrobial resistance gene markers did show a significant change in abundance in the saliva samples of all four astronauts across their collection times. These results provide insight for future ISS microbial monitoring studies and targets for antimicrobial resistance screenings.

Patterns of salivary microbiota injury and oral mucositis in recipients of allogeneic hematopoietic stem cell transplantation

Oral mucositis (OM) is a common debilitating dose-limiting toxicity of cancer treatment, including hematopoietic stem cell transplantation (HSCT). We hypothesized that the oral microbiome is disturbed during allogeneic HSCT, partially accounting for the variability in OM severity. Using 16S ribosomal RNA gene sequence analysis, metabolomic profiling, and computational methods, we characterized the behavior of the salivary microbiome and metabolome of 184 patients pre- and post-HSCT. Transplantation was associated with a decrease in oral α diversity in all patients. In contrast to the gut microbiome, an association with overall survival was not detected. Among 135 patients given methotrexate for graft-versus-host disease prophylaxis pre-HSCT, Kingella and Atopobium abundance correlated with future development of severe OM. Posttransplant, Methylobacterium species were significantly enriched in patients with severe OM. Moreover, the oral microbiome and metabolome of severe OM patients underwent distinct changes post-HSCT, compared with patients with no or mild OM. Changes in specific metabolites were well explained by microbial composition, and the common metabolic pathway was the polyamines pathway, which is essential for epithelial homeostasis. Together, our findings suggest that salivary microbial composition and metabolites are associated with the development of OM, offering new insights on pathophysiology and potential avenues of intervention.

A Randomized, Double-Blind, Placebo-Controlled Trial to Assess the Acidogenic Potential of Dental Biofilms through a Tablet Containing Weissella cibaria CMU

The possibility of preventing dental caries by taking probiotic bacterium Weissella cibaria (W. cibaria) CMU tablets to alter the pH of the dental plaque in the oral cavity was evaluated. A randomized, double-blind, placebo-controlled trial was performed on adults aged 20 years or older with 20 or more natural teeth. Ninety-two people underwent dental scaling before being randomly assigned to the experimental group (n = 49) or the control group (n = 43). Depending on the group they belonged to, W. cibaria CMU or the placebo was administered to them once daily for 8 weeks before bedtime. Twenty-four subjects were later excluded from the study because the week 8 dosing was not smoothly performed, for a final subject count of 68. The Cariview test was used to evaluate the amount of acid produced by the dental plaque to assess the risk of caries. The results showed that although there was no significant difference between the results of the two groups, the intake of the W. cibaria CMU tablets eliminated the risk of developing dental caries from acid production in the oral flora because the W. cibaria colonizes and lives in the dental plaque and the oral cavity and suppresses acids.

The oralome and its dysbiosis: New insights into oral microbiome-host interactions

The oralome is the summary of the dynamic interactions orchestrated between the ecological community of oral microorganisms (comprised of up to approximately 1000 species of bacteria, fungi, viruses, archaea and protozoa - the oral microbiome) that live in the oral cavity and the host. These microorganisms form a complex ecosystem that thrive in the dynamic oral environment in a symbiotic relationship with the human host. However, the microbial composition is significantly affected by interspecies and host-microbial interactions, which in turn, can impact the health and disease status of the host. In this review, we discuss the composition of the oralome and inter-species and host-microbial interactions that take place in the oral cavity and examine how these interactions change from healthy (eubiotic) to disease (dysbiotic) states. We further discuss the dysbiotic signatures associated with periodontitis and caries and their sequalae, (e.g., tooth/bone loss and pulpitis), and the systemic diseases associated with these oral diseases, such as infective endocarditis, atherosclerosis, diabetes, Alzheimer's disease and head and neck/oral cancer. We then discuss current computational techniques to assess dysbiotic oral microbiome changes. Lastly, we discuss current and novel techniques for modulation of the dysbiotic oral microbiome that may help in disease prevention and treatment, including standard hygiene methods, prebiotics, probiotics, use of nano-sized drug delivery systems (nano-DDS), extracellular polymeric matrix (EPM) disruption, and host response modulators.

Salivary Microbiome in Pediatric and Adult Celiac Disease

The human salivary microbiota includes hundreds of bacterial species. Alterations in gut microbiota have been explored in Celiac Disease (CD), but fewer studies investigated the characteristics of salivary microbiome in these patients, despite the potential implications in its pathogenesis. Indeed, some recent studies suggested that the partial digestion of gluten proteins by some bacteria may affect the array of gluten peptides reaching the gut and the way by which those are presented to the intestinal immune system. The available clinical studies investigating the salivary microbiota in children and adults, are insufficient to make any reliable conclusion, even though some bacterial species/phyla differences have been reported between celiac patients and controls. However, the salivary microbiome could correlate better with the duodenal microbiota, than the fecal one. Therefore, further clinical studies on salivary microbiome by different and independent research groups and including different populations, are advisable in order to explore the usefulness of the salivary microbiome analysis and understand some aspects of CD pathogenesis with potential clinical and practical implications.

The microbiome of oral cavity patients with periodontitis, adhesive and biofilm forming properties

The microbiome of oral cavity in healthy people and patients with periodontitis was analyzed to determine their adhesive properties and the ability to form biofilms. The study involved 2 groups: healthy, 18 people, and an experimental group, 20 patients with chronic generalized periodontitis moderate severity of the disease. The average age of the studied people was 35-45 years. Material - dental plaque, scraping from the mucous membrane of the back of the tongue, the contents of the periodontal groove and periodontal pocket, as well as oral fluid. The main method of diagnostic was bacteriological. The average adhesion index (AAI) was used to determine adhesion level of microorganisms to epithelial cells of oral cavity’s mucous membrane. The microbiota’s ability to form biofilm was tested on glass and plastic surface. The microbiota of oral cavity of patients with periodontitis was characterized by decrease in the frequency of bacteria of the genera: Streptococcus, Peptostreptococcus, Peptococcus, and an increase in Staphylococcus aureus, Veillonella spp., Bacillus spp. The microbiota of the oral cavity of patients with generalized periodontitis has a greater ability to adhere to the cells of the mucous membrane than in healthy people, while their ability to form biofilms and exhibit pathogenic properties is enhanced. The biofilm formation of microorganisms in healthy and sick people differs both on glass and on plastic surfaces.

Characterization of the Oral Microbiome of Medicated Type-2 Diabetes Patients

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease that is becoming a significant global health care problem. Several studies have shown that people with diabetes are more susceptible to oral problems, such as periodontitis and, although the causes are still inconclusive, oral microbiota is considered to play a major role in oral health. This study aimed to characterize the oral microbiome of a sample representing T2DM patients from Portugal and exploit potential associations between some microorganisms and variables like teeth brushing, smoking habits, average blood sugar levels, medication and nutrient intake. By sequencing the hypervariable regions V3-V4 of the 16S rRNA gene in 50 individuals belonging to a group of diabetes patients and a control group, we found a total of 232 taxa, from which only 65% were shared between both groups. No differences were found in terms of alpha and beta diversity between categories. We did not find significant differences in the oral microbiome profiles of control and diabetes patients. Only the class Synergistia and the genus TG5, which are related to periodontitis, were statistically more frequent in the control group. The similar microbiome profiles of medicated diabetics and the control group indicates that the relationship between the T2DM and the oral microbiome might be more related to either the lifestyle/diet rather than diabetes per se. Moreover, this study provides, for the first time, insights into the oral microbiome of a population with a high prevalence of diabetes.

The role of sugar-rich diet and salivary proteins in dental plaque formation and oral health

BACKGROUND

Dental plaque is a complex colorless film of bacteria that develops on the surfaces of teeth. Different mechanisms of microbial adhesion to tooth surfaces exist. Both non-specific and specific types of adherence have been anticipated.

HIGHLIGHT

The present review evaluated the effect of sugar-rich diet and salivary proteins on oral hygiene and dental plaque development.

CONCLUSION

The oral microbiota is essential for maintaining and reestablishing a healthy oral cavity. Different types of sugars have different effects on the inhibition and formation of dental plaque. The peptides, proteins, and amino acids secreted by parotid glands in the oral cavity facilitate neutralizing the acidity in dental plaque and preventing dental caries. A properly balanced diet is crucial for both a healthy oral cavity and the oral microbiome.

Relationship between bariatric surgery outcomes and the preoperative gastrointestinal microbiota: a cohort study

BACKGROUND

The composition of the gastrointestinal microbiota is associated with obesity. We hypothesized that the gut microbiota influences the outcomes of bariatric surgery.

OBJECTIVES

We aimed to analyze using oral swabs and stool samples the microbiota of patients with morbid obesity who were undergoing laparoscopic sleeve gastrectomy (SG).

SETTING

A university hospital in Poland.

METHODS

This prospective cohort study was conducted between November 2018 and June 2019. Participants underwent SG or no surgery (controls). Results were then analyzed as a group 1 (surgical participants who achieved a percentage of excess weight loss [%EWL] >50%), group 2 (surgical participants who achieved a %EWL <50%), and group 3 (nonsurgical controls). %EWL was measured 6 months following surgery. Before surgery, oral swabs were obtained and stool samples were provided. The endpoint was the composition of the gut microbiota.

RESULTS

Group 1 comprised 19 participants, group 2 comprised 11 participants, and group 3 comprised 16 participants. No participants were lost to follow-up during the study. Participants in group 1 had an oral microbiota that was enriched in the phyla Proteobacteria, and Bacteroidetes. Their intestinal microbiota was enriched in the Proteobacteria. In contrast, the oral microbiota of group 2 was enriched in the Actinobacteria and the intestinal microbiota was enriched in the phyla Bacteroidetes and Firmicutes.

CONCLUSIONS

The compositions of the microbiota of the oral cavity and large intestine are related to the weight loss achieved following SG.